The invention relates to a method and a device for supplying lubricant to a plurality of lubricating points of an I.S. glassware forming machine.
Central lubrication systems for I.S. glassware forming machines are conventionally known and operate on the basis of loss lubrication and comprise only one lubrication circuit. The length of the time interval between two lubrication processes depends upon the lubricating point that must be re-lubricated first. Lubricant metering devices of the same size are generally used in these systems so that the amount of lubricant output per lubrication process of a lubricating cycle is the same for all lubricating points, independent of the geometric size of the lubricating point. As a result, the majority of lubricating points are supplied with too much lubricant and too frequently.
In order to reduce this type of over-lubrication, systems with a series of several lubrication circuits have been used for a while. Each lubrication circuit comprises a group of lubricating points that are combined according to the criterion of a reasonable length for the lubricating interval. In this manner, each group of lubricating points is supplied with lubricant by the dedicated lubrication circuit in a lubricating cycle independent of the other lubrication circuits.
Although controlling the lubricating interval according to need in this manner represents a considerable improvement compared with the central lubrication systems first mentioned, provision is generally made in these known multi-circuit lubrication systems for the times to be adjusted once and to remain unaltered for the remainder of the service life of the I.S. glassware forming machine. However, this does not take into account the fact that the majority of glassware forming machines are subject to frequent job changes, wherein the size of the hollow glass article, the machine speed and other parameters are modified. In the meantime, in practice multi-circuit lubrication systems of this type having a control unit have become known (companies Graphoidal Ltd., Dronfield, United Kingdom and Graphoidal Developments Ltd., Chesterfield, United Kingdom), wherein the time interval lengths of a lubrication circuit can be changed independently of each other by means of operator programming. This allows lubricant to be saved which represents a considerable improvement in particular in the use of synthetic oil not only with respect to the impact on the environment but also financially (“Throwing it all away”, A. Lawrence, Glass 79 (2002)5, page 162; “Managing modern lubricants”, A. Lawrence, Glass 80 (2003)2, pages 52-53). Each lubrication circuit can be supplied independently via only a single pump via a respective valve having different preset time interval lengths or idle times.
Although such a lubrication system basically allows different lubricating points to be lubricated at different intervals, it is left to the operator to decide how to divide the circuit and how often it is lubricated. The amount of lubricant provided at the lubricating points is not controlled. In this regard, Graphoidal Developments Ltd. describes the option of providing different time interval lengths for different mechanisms, such as the mechanics of a respective section of the I.S. glassware forming machine, the plunger mechanism, the feeder mechanics, the shearing mechanism, the machine belt and handling elements in the forming region. Thus, grouping the lubricating points in the lubrication circuit is suggested, wherein the spatial arrangement forms the criterion for the allocation. However, this criterion is not really suitable in terms of reducing the consumption of lubricant since the temperature of the respective lubricating point is of utmost importance for evaporation losses of the lubricant. However, the temperatures of the lubricating points could differ greatly from each other even in the case of a relatively similar spatial arrangement. For example, the temperature values in the region of the section mechanics are spread over a range of up to 200° C.
In addition to such a method of the generic type or such a device of the generic type, there is the following Prior Art:
EP 1 043 483 A1 discloses the provision of characteristic field-related control of lubricant pumps for internal combustion engines, wherein provision can also be made to measure the temperature at a point to be lubricated. However, the characteristic field relates to desired pressure values of the lubricant.
DE 200 22 934 U1 discloses the consideration of the evaporation of lubricant per se (cf. page 5, last paragraph).
DE 694 33 065 T2 relates specifically to supplying a roller bearing with lubricant, wherein the use of characteristic fields to control the metering of the lubricant is also basically mentioned.
Reference is also made to DE 35 32 203 A1 that relates to a particular manner of lubricating an opening casting mold of an I.S. glassware forming machine.